Cutting method for a diamond with low depth percentage and resultant cut diamond

ABSTRACT

A gemstone, and a method for cutting a gemstone, such that the resulting gemstone has a total depth percentage of between 38-55% but still provides for a brilliant cut without having face main facets intersect a cullet.

BACKGROUND OF THE INVENTION Field of the Invention

This disclosure is related to the field of diamond cutting, and, in particular, it relates to a method of forming a faceted gem having a decreased depth percentage compared to a traditional cut.

Description of the Related Art

Faceted gemstones, and particularly cut diamonds, are effectively extremely precise, and very complex, light prisms. A well cut diamond is a solid, ideally transparent, piece of material that includes a large number of faces or “facets” which are cut into its external surface. Those facets serve to direct light within the structure of the diamond so that the diamond is ideally designed to capture as much light as possible, and then redirect that light to the eye of the user. The reflected and refracted light allows for patterns in the facets to be seen through the top or “table” of the diamond. Entering light is reflected and refracted inside the diamond to produce brilliance (the reflection of while light), fire (the reflection of only a portion of the white light producing color), and scintillation (the “flashing” effect of white or colored light as the diamond moves due to reflection effects sending light toward or not toward the viewer's eye).

As diamond cutting is effectively an art, a number of different shapes have been devised over time to unproved particular light handling properties of the diamond. While the possible shapes are nearly infinite, they share a number of fairly common elements in diamond and gemstone cutting. A diamond for jewelry is almost always cut to have a top and a bottom, the top or “crown” being the side which is viewed, while the bottom or “pavilion” is the side positioned toward the body of the wearer. The crown is typically at the top of the diamond, a pavilion at the bottom of the diamond, and a girdle disposed therebetween. The crown generally is a roughly dome-shaped element having multiple facets around its perimeter, but focused on a flat table at the center which serves as the facet for directing light into the viewer's eye.

The table generally allows the viewer to look into the diamond and view the pavilion facets (or more accurately light reflecting from them) through the table. In order to direct light, the pavilion is usually longer (deeper) than the crown and ends in a point or a smaller flat facet called a cullet. The size (depth) of the pavilion is typically desired because the pavilion is primarily used to gather light (or reflect entering light from the crown) toward the table. Diamonds with a smaller pavilion are generally considered to have been cut shallow, and have traditionally produced undesirable reflection and refraction appearance. The cullet is generally intended to inhibit the diamond from having the pavilion end in a sharp point to inhibit damage to both the stone and the wearer. Generally speaking, each facet of the crown has a corresponding facet in the pavilion but this is not required and the facets in the crown and pavilion are generally differently angled to produce expected patterns.

Within this broad overview, there are an enormous number of variations of cut, however. Again, speaking generally, there are two major distinctions related to cut. The first is the general type of cut while the second is the shape of the diamond. The general type of cut is generally selected from two categories. The first of these is a stepped cut which is a cut where the crown and pavilion facets are generally cut all the way around the diamond so as to provide the diamond with a series of “steps” up the crown toward the table and down the pavilion. Stepped cuts are generally more common on colored gemstones (and are particularly common on emeralds) while not being particularly common on diamonds as they generally produce less intricate patterns. The uncommon use of stepped cuts in diamonds is primarily because the stepped arrangement provides for fewer possible internal angles of reflection and, therefore, while the stone itself can look very interesting, its light handling abilities may be diminished compared to the alternative. The second general type of cut is often loosely referred to as a “brilliant” cut. Technically, an actual brilliant cut is one type within the broad category (having 57 or 58 facets and on a round diamond), but the category is often referred to due to similarity in facet positioning compared to stepped cuts. In a brilliant cut (or a modified brilliant cut as it is sometimes referred to when applied to a non-round diamond), relatively small facets are arranged around the crown and pavilion with large numbers of angles existing between them.

The second basic category is the shape of the diamond. The shape of the diamond is generally indicated primarily by the shape of the girdle when viewed from the table. The diamond in FIG. 2, for example, is an oval cut so the general shape of the girdle (which is coplanar with the drawing sheet in this image) is an oval. The primary girdle shapes are ovals, rounds, squares, rectangles, pears (or teardrops), marquise (a symmetric lens shape such as a vesica piscis) and cushions (generally rounded quadrilaterals, squares with rounded corners (and sometimes rounded sides), and “squircles”) however other specialist shapes such as hearts are produced. Often, cuts which are not round arc referred to as “fancy” and are generally substantially less common than round cuts.

By far the most popular cut is the round brilliant cut which is the cut most consumers associate with diamond engagement rings. Further, a large number of custom or proprietary cuts are essentially modifications of the round brilliant. A traditional round brilliant provides for 57 facets (58 if there is a cullet present) while modified versions of the cut can provide fewer facets, or dramatically more (some modern cuts may have facets numbering m the hundreds). The traditional round brilliant cut was developed by Marcel Tolkowsky and because of its amazing light handling properties the round brilliant is often referred to as a Tolkowsky cut or ideal cut. The general layout of an ideal cut can generally be readily translated into other shapes of diamonds by simply modifying the specific size and positioning of facets to accommodate the different girdle shape. These are usually called “modified brilliant” cuts and generally, in this disclosure, these are the types of cuts discussed. Thus, when this disclosure refers to a “modified brilliant” cut it will generally be a cut having 58 facets in the pattern of a Tolkowsky cut, but on an non-round stone.

Even within a particular type of cut, such as the round brilliant, the actual light handling properties of a diamond commonly depend on how the cut compares to a specific target shape. In effect, there is a “best” version of every cut, where the various facet angles produce what is considered to be the “best” light handling. As each of the 58 facets is cut individually by a diamond cutter and the cutting process is extremely difficult. It requires specialized knowledge, tools, equipment, techniques, and expertise. As such, the practice of gem cutting is practiced by highly skilled practitioners or, increasingly, by very accurate machines. Further, raw gemstones take whatever shape nature imparts, and these natural shapes generally are not always ideal for use in jewelry or to make a particular end shape of cut gemstone. Cutting can result in substantial loss of weight to the stone and since size is one of the primary determiners of value, not wasting excess during the cutting process is obviously preferred.

Because the cutting process, and the resultant carat weight of the stone, is so dependent on the original diamond crystal, the crystal will often dictate the resultant shape selected. Thus, a raw stone which is more suitable for a round brilliant will generally be made into a round brilliant cut, but other raw stones will be more suitable for square cuts or for shapes such as ovals. Even within this shape selection there are considerations. For example, a crystal may be made into two smaller stones, or one larger one. Further, a crystal may not allow for the creation of a stone with ideal proportions without excessive waste, or it may be possible to form a stone into a single ideal cut stone, or into multiple slightly less than ideal cuts. A diamond cutter has to select the best use of the underlying crystal to maximize their return on investment. The natural variation is particularly relevant on very large diamonds. Due to the rarity of very large diamonds, it is often more desirable to maintain the weight of the stone even if compromises must be made on the quality of the cut, because the stone's primary value is its exceedingly large size.

Because of the nature of brilliant cuts, the brilliant cut tends to require substantial height (depth) to be close to the target shape. This is immediately apparent by examining a diamond engagement ring where the stone generally extends quite a distance from the band. This height is a major element of the cut as the height impacts if light directed into the stone is directed out of the table, or in another direction where it is less likely to be viewed. The height of a stone is generally discussed in jewelry as the depth percentage. Total depth percentage is generally defined the depth divided by the average girdle diameter. It is known in the art that total depth, with respect to a gemstone, is the distance from the table to the bottom point of the stone. The average girdle diameter is generally calculated as the average of the minimum girdle diameter and the maximum girdle diameter, using an arithmetic mean. It is widely believed among gem cutters that a depth percentage of around 58-64% produces the most attractive and optically desirable stone characteristics for brilliant cuts.

One problem with round brilliant and other designs, however, is that this depth percentage is not always practical. A natural raw diamond may be of such a shape that the stone will not accommodate greater than 58% depth percentage without having to undesirably reduce the girdle diameter and lose substantial weight. Similarly, tall diamonds often look smaller than they are in and may not lend themselves to certain settings. For example, smaller diamonds, when cut to ideal proportions, may not be readily useable in pendants because the stone will not sit with the table facing outward, but will rotate making it look less attractive. To compensate for this, the diamond may need to be mounted in a heavier setting to keep it straight This may reduce the light entering the diamond (reducing the effect of the ideal cut) and may make the diamond appear smaller due to the heavy mount and that the depth is not visible from the table.

One way to avoid the problems of tall stones is simply to cut them to have a decreased depth percentage. While this works for certain raw diamonds and can make the stones more readily mountable in these types of settings, it can result in less desirable appearance. Stones with an insufficient depth percentage are often referred to as having been “shallow” cut and they will typically have light leakage from the side of the stone. In effect, light is reflected within the diamond, but instead of being directed out the table, the angles are insufficient and result in light going out the sides of the stone instead of the top. Shallow stones, therefore, are often undesirably uninteresting in light handling characteristics and considered dramatically inferior.

Because of these and other issues, there is a need in the art to develop a diamond cut, and particularly a modified brilliant style of cut for use with flat diamonds or diamonds with a depth percentage of 58% or less. These cut diamonds would generally exhibit superior brilliance and/or fire compared to other diamonds having a reduced depth percentage cut using traditional brilliant cutting patterns. Further, because of the reduced depth percentage, the diamond will generally appear physically larger than a corresponding diamond cut to more traditional proportions as its girdle is comparatively larger to more traditionally cut stones of similar weight. Such a cut is particularly useful for fancy cut diamonds (e.g. oval, cushion, marquise, and pear) where the shape is often a more desirable element in resultant jewelry designs.

SUMMARY OF THE INVENTION

The following is a summary of the invention in order to provide a basic understanding of some aspects of the invention. This summary is not intended to identify key or critical elements of the invention or to delineate the scope of the invention. The sole purpose of this section is to present some concepts of the invention in a simplified form as a prelude to the more detailed description that is presented later.

Because of these and other problems in the art, described herein, among other things, is a method of cutting and the resultant cut gemstone where the resultant cut gemstone includes: a crown and a pavilion separated by a girdle, each of the crown and the pavilion being cut to have multiple facets, the pavilion facets including: a collet facet; a belly main facet contacting the girdle facet and the cullet facet; a face main facet contacting the girdle facet but not the cullet facet; a shoulder main facet between the belly main facet and the face main facet; at least two half facets between the belly main facet and the shoulder main facet; and at least two half facets between the shoulder main facet and face main facet; wherein the belly main facet has a facet angle between 28 and 38 degrees; wherein the face main facet has a facet angle between 30 and 38 degrees; and wherein a total depth of the gemstone is between 45 percent and 55 percent of a &meter of the girdle.

In an embodiment, the cut gemstone is a cut diamond.

In an embodiment of the cut gemstone, the gemstone girdle may be generally an oval, a marquise, a pear, or a cushion.

In an embodiment of the cut gemstone, the crown has a crown angle; the pavilion has a pavilion angle; and the crown angle is greater than the pavilion angle by between 6 degrees and 12 degrees inclusive.

In an embodiment of the cut gemstone, a twist angle of the pavilion is between 30 and 40 degrees.

In an embodiment of the cut gemstone, the shoulder main facet has a facet angle of between 25 and 33 degrees.

In an embodiment of the cut gemstone, the facet angle of the shoulder main facet is less than the facet angle of the face main facet.

In an embodiment of the cut gemstone, the cullet is in the shape of an elongated hexagon.

In an embodiment of the cut gemstone, the shoulder main facet and the belly main facet meet at a first portion of a line of intersection; the at least two pavilion half facets between the shoulder main facet and the belly main facet meet at a second portion of the line of intersection; and the first portion of the line of intersection is equal to or longer than the second portion of the line of intersection.

In an embodiment of the cut gemstone, the crown includes a kite facet, at least two crown half facets, a table, and a star facet.

In an embodiment of the cut gemstone, an average table diameter is between 54 and 64 percent of an average diameter of the girdle.

In an embodiment of the cut gemstone, the cut gemstone includes 58 total facets.

In an embodiment of the cut gemstone, the shoulder main facet contacts the girdle facet and the cullet facet.

In an embodiment of the cut gemstone, the cullet has an average diameter of less than 5 percent the average diameter of the girdle.

There is also described herein, in an embodiment, a cut gemstone including: a crown and a pavilion separated by a girdle, each of the crown and the pavilion being cut to have multiple facets, the pavilion facets including: a cullet facet; a belly main facet contacting the girdle facet but not the cullet facet; a thee main facet contacting the girdle facet but not the cullet facet; a shoulder main facet between the belly main facet and the face main facet; at least two pavilion half facets between the belly main facet and the shoulder main facet; and at least two pavilion half facets between the shoulder main facet and face main facet; wherein the belly main facet has a facet angle between 28 and 38 degrees; wherein the face main facet has a facet angle between 30 and 38 degrees; and wherein a total depth of the gemstone is between 35 percent and 55 percent of a diameter of the girdle.

In an embodiment of the cut gemstone, the shoulder main facet and the belly main facet meet at a first portion of a line of intersection; the at least two pavilion half facets between the shoulder main facet and the belly main facet meet at a second portion of the line of intersection; and the first portion of the line of intersection is equal to or longer than the second portion of the line of intersection.

In an embodiment of the cut gemstone, a twist angle of the pavilion is between 30 and 40 degrees.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a side view of an embodiment of a flat (depth percentage less than or equal to 55%) diamond with a pavilion cut in accordance with the present disclosure

FIG. 2 provides a top (crown) view of the cut oval diamond of FIG. 1.

FIG. 3 provides a bottom (pavilion) the cut oval diamond of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

The following detailed description and disclosure illustrates by way of example and not by way of limitation. This description will clearly enable one skilled in the art to make and use the disclosed systems and methods, and describes several embodiments, adaptations, variations, alternatives and uses of the disclosed systems and methods. As various changes could be made in the above constructions without departing from the scope of the disclosures, it is intended that all matter contained in the description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

The present disclosure is directed to a method for shaping a gemstone such that the resulting stone has a total depth percentage of less than 55%. Ideally, the depth percentage is less than 50% and will commonly be from around 38% to around 45% making the diamond traditionally fall into a category of being very flat. As described herein, this method and resulting cut shape, is suitable for use with any technique for shaping any gemstone, but is believed particularly useful for diamonds. This method may be used for any shape of cut gemstone, but is particularly useful for fancy shapes including, but not limited to, cushion, marquise, oval, round, and pear cuts. This disclosure will discuss specifically how to apply sizing and facet arrangement to oval shapes, but one of ordinary skill will understand how to adapt the teaching herein to other cuts as the principles remain the same across different shapes.

In general, the present method of cutting, and the resultant cut gemstone, provide for improved light handling through the use of steeper angles applied to the pavilion main facets than would traditionally be done with a stone of the indicated depth percentage. This is commonly performed through the inclusion of a cullet (119) which will typically be hexagonal, octagonal, or parallelogram in shape and which will generally only intersect some of the pavilion main facets (301), (303), and (305). Specifically, the pavilion face main facets (301) (at the elongated portions of the stone) will generally not intersect with the cullet (119). The inclusion of a cullet (119) importantly allows for the pavilion main facets (301), (303), and (305) to go to a greater while still providing a base to the stone. It particularly allows for the pavilion face main facets (301), and the pavilion belly main facets (303) to have steeper angles than they would in a traditional brilliant cut (which would result in a shallow cut with a stone of this total depth percentage).

FIG. 1 provides a side view of an embodiment of a low depth brilliantly cut flat oval diamond with an 8 main configuration in the pavilion cut in accordance with the present disclosure. FIG. 2 provides a top view of the cut oval diamond of FIG. 1. FIG. 3 provides a bottom view of the cut oval diamond of FIG. 1. The drawings will generally all be discussed interchangeably. The diamond shown in the drawings provides for the traditional 58 facet positioning for a modified brilliant cut oval diamond (with a cullet) and, for ease of discussion, the various facets are labeled so they may be referred to herein specifically. The crown (103) includes the table (109), crown main or kite facets (201), (203), and (205), crown star facets (215), and crown half facets (207) and (209). The pavilion (105) includes the pavilion main facets (301), (303) and (305), pavilion half facets (207) and (209) and the cullet (119). A girdle (107) separates the crown (103) and pavilion (105). It should be recognized that the numbering system is such that the facets in the crown (103) aligned with a facet in the pavilion (105) generally share the same last two digits but the facets in the crown begin with “2” while those in the pavilion begin with “3”.

While the above provides the basic facets, it should be recognized that both the main facets and half facets each utilize two different numbers. This is to reference the specific location of the facets as this diamond is not round and thus facet positioning relative to the shape of the stone is important. Specifically, the main facets at the elongated ends of the stone (head and tail) are referred to as crown face main facets (201) and pavilion face main facets (301). The main facets positioned at the constricted ends are referred to as the crown belly main facets (203) and pavilion belly main facets (303). Finally, the main facets located between face and belly mains (essentially around the curve) will be referred to as the crown shoulder main facets (205) and pavilion shoulder main facets (305). With regards to the half facets, a thee half facet (209) or (309) is positioned between a shoulder half facet (207) or (307) and a face main facet (201) or (301) or belly main facet (203) and (303) while a shoulder half facet (207) or (207) is positioned between a face half facet (209) or (309) and a shoulder main facet (203) or (303).

It should be recognized that FIGS. 1 through 3 provide for an oval cut, the positioning and labeling of facets would apply to other limey cuts as other fancy cuts in the modified brilliant form are generally just modifications of the oval. For example, a marquise (lens) shape would simply have the face main facets (201) and (301) produce a point, a pear shape would have one end like a marquise and the other like an oval, and a cushion could be considered similar to an oval without as much elongation along one axis.

In older to provide for improved appearance in a stone with decreased depth percentage, it should first be recognized what is meant by decreased depth percentage. Regardless of shape, the total depth percentage of diamonds cut in accordance with this disclosure will generally be less than 55%, preferably less than 52%, preferably less than 50%, preferably less than 45%, and more preferably between 38% and 45%.

Within the above range, generally a substantially increased amount of the total depth will also be in the crown as opposed to the pavilion. In many respects, the present embodiments will provide for a crown which is only slightly shallower than a standard modified brilliant corresponding to the shape and may be over the same relative depth. Instead of discussing this herein in conjunction with depth percentage, it is actually more logical to discuss it in terms of pavilion and crown angles. It is generally preferred that the crown angle (509) and the pavilion angle (519) be different by about 5 to about 12 degrees with a difference of around 6 to around 8 degrees being preferred. It is also generally be preferred that the crown angle (509) be about 28 degrees to about 38 degrees (alternatively between 30 and 36 degrees). The pavilion angle (519) will also typically be around 28 to around 38 degrees (alternatively between 30 and 36 degrees). The reason for the similar range is that typically a lower pavilion angle will be used with a higher crown angle and vice-versa. It is generally preferred, however, that the crown angle (509) be greater than the pavilion angle (519) which is backward to a more traditional brilliant cut. It should be recognized that the proposed angles are subject to some variation and interplay based on total available depth as stones on the deeper end of the total depth percentage spectrum are likely to have different arrangements than stones on the shallower end and the natural variations within stone formation mays encourage particular selections. The table (109) will generally also be of traditional desired size having an average diameter of around 54 percent to around 63 percent of the average diameter of the girdle (107).

As should be apparent from the above, by maintaining a generally similar crown angle (509) to traditional cuts, the crown facets will generally be broadly similar to the cutting of standard modified brilliant cuts and will commonly be within ranges perceived as high quality for standard modified brilliant cuts. In the present embodiment, most of the change in the cut is actually made to the pavilion (105) of the diamond. In this way, the diamond, when viewed from the table (109), will look quite similar to a standard modified brilliant cut based on positioning of facets the crown (103) while haying better light direction from the pavilion (105).

The pavilion (103) of an exemplary stone from an embodiment is shown best in FIG. 3. In the embodiment of FIG. 3, the main facets are arranged so as to have steeper angles than would be traditional on a stone this flat. This is generally done through modification of the points of interaction between facets and the twist imparted to the facets which can alter their side to side width. Speaking broadly, changes made to the stone are to tilt out the main facets (301), (303), and (305). This is performed generally by including a cullet (119) which serves to allow the bottom ends of the pavilion main facets (201), (203), and (205) to be spaced further from each other. A second change is to not have all the pavilion main facets (201), (203), and (205) reach the cullet at all. This provides for the bottom ends of the main facets to be further pushed from each other. For fancy cuts (which are often non-symmetric) generally the pavilion face main facets (301), which are at the elongated ends, are moved from contacting the cullet (119) first, followed by the pavilion belly main facets (303). The pavilion shoulder facets (305) will generally contact the cullet (119) in virtually all arrangements. While this pattern is preferred, for certain cuts it may be desirable to move the pavilion main facets (301), (303), and (305) away from the cullet in a different pattern. It should be recognized that the shape of the cullet (119) which would traditionally be octagonal, is commonly reduced to an elongated hexagon or parallelogram as various main facets cease contacting it.

In the embodiment of FIG. 3, the cullet facet (119) is preferably present and will gene rally have an average diameter of around 0.01% to around 6% of the average diameter of the girdle (107) with a preference being toward the larger end of around 4% to around 6%. It is, therefore, substantially smaller than many older cut diamonds which utilized a large cullet, but larger than many modern diamonds where they are used sparingly if at all (often to preserve weight). As indicated above, the presence of a cullet (109) pushes the main facets to a steeper angle as the main facets do not need to actually reach a point but simply need to reach the cullet (119).

In the embodiment of FIG. 3, the pavilion face main facets (301) do not reach the cullet (119) but the pavilion belly main facets (303) do. This will be a common arrangement to provide for similar angle between the pavilion belly main facets (303) an the pavilion face main facets (301) as discussed later since the pavilion belly main facets (303) have less distance to travel and can more readily be made at steeper angles. As can be seen in FIG. 3, terminating, the pavilion face main facets (301) shy of the cullet (119) creates a line of intersection (351) between the two pavilion shoulder main facets (305) on either side of the pavilion face main facets (301). It should be apparent that having this premature termination results in the pavilion face main facets (301) having a steeper angle than they would if they extended to the cullet (119). The diamond therefore gains artificial depth. Depending on the specific embodiment, the pavilion face main facets (301) will preferably have an angle of around 30 degrees to around 36 degrees.

The belly main facets (303) will generally reach to the cullet and will commonly be arranged to have a similar angle to the face main &cos (301). Specifically, the belly main facets (303) will generally have an angle of around 28 to around 36 degrees. The belly main facets have a greater window of variation because in most fancy cuts the stone is not round. As discussed above, this type of cut is particularly useful in fancy shaped diamonds. In such diamonds, one dimension is always elongated compared to the other. Because of that, the pavilion face main facets (301) and pavilion belly main facets (303) will have different distances to travel to reach the cullet (119) if they are at the same angle. Specifically, as can be seen in FIG. 3, the pavilion belly main facets (303) generally have to travel less distance to reach the cullet (119) than the pavilion face main facets (301). Thus, the pavilion belly main facets (303) will often reach the cullet (119) even while the pavilion face main facets (301) do not.

It should be noted that while the pavilion belly main facets (303) reaching the cullet (119) is generally preferred, it is not required and in some stones, particularly those toward the lower end of the depth percentage ranges presented above, the pavilion belly main facets (303) may also fail to reach the cullet (119). In this particular embodiment where neither the pavilion face main facets (301) or the pavilion belly main facets (303) react the cullet (119), the pavilion shoulder main facets (305) will generally define the cullet (119).

The pavilion shoulder main facets (305) generally cannot be at as steep of an angle as the pavilion face main facets (301) or pavilion belly main facets (303). Therefore, the pavilion shoulder main facets (305) will generally be at an angle of between about 25 degrees and about 33 degrees. Because the pavilion shoulder main facets (305) essentially always contact the cullet (119) and because the pavilion shoulder main facets (305) generally have less distance to travel to the cullet (119) than the pavilion face main facets (301), the angle of the pavilion shoulder main facets (305) will generally always be less than that of the pavilion face main facets (301).

While the pavilion main facets (301), (303), and (305) provide for much of the brilliance of a cut gen stone, it should be recognized that with their position adjustment, the pavilion halves (307) and (309) have also been adjusted both to allow the main facets to be positioned as indicated while still making a symmetrical cut and to provide for their illumination effects. Normally, paired pavilion halves would be generally symmetrical about each other, but in the present diamond that is not necessarily the case. Specifically, the pavilion shoulder halves (307) will generally have an angle of about 27 to about 32 degrees while the pavilion face halves (309) will commonly also be around 27 to around 32 degrees but will typically always be at greater angle than the pavilion shoulder halves (307). Much of the arrangement of the halves is simply to present angles which allow for the corners of the stone to be turned between the main Facets (301), (303), and (305) when the main facets (301), (303), and (305) are at the angles contemplated above. For example, as the pavilion shoulder main facets (305) will have less angle than the pavilion thee main facets (301) (and usually the pavilion belly main facets (303) also), the shoulder half facets (307) will typically have less angle than the face half facets (307) to allow for transition between them while keeping all facet faces flat and the stone symmetrical.

In many respects, the pavilion half facet (307) and (309) angles are chosen to simply get angles between the pavilion main facets (301), (303), and (305) with a facet surfaces using the correct 58 facet arrangement of a modified brilliant. How they are positioned is actually commonly best understood by using the twist (529) of the diamond. Twist (529) is a characteristic of a diamond commonly used by diamond cutters, but which is often not used in the retail sale of jewelry. Twist (529) is the angle between adjacent main facets. Generally, the twist (529) for the pavilion (105) and the twist (529) for the crown (103) will be the same as the facets are concentrically arranged between the two, thus while the twist (529) shown in FIG. 2, it would apply equally to FIG. 3.

In the present oval diamond, a twist of between about 30 degrees and about 40 degrees is preferred. Generally the rounder the diamond, the greater the twist (529), but in the present embodiments, keeping the twist in this range regardless of shape (e.g. also using the same twist range on marquise, pear, and cushion shapes) while simply making the halves (307) and (309) steeper on rounder stones (for example, cushion cuts or rounder ovals) is expected to provide for improved light handling.

While the above has discussed a great deal of the facet positions and angles, there is also one more element of facet intersection to discuss. As contemplated above, the pavilion face main facets (301) and pavilion belly main facets (303) are generally positioned so as to be at a greater angle than would be expected given the depth of the stone. In many respects, this results in them being “pushed out” at the cullet (119). Because of this, the line of intersection between the pavilion main facets (301), (303), and (305) and the neighboring half facets (307) and (309) is moved and its angle is altered. This can be seen in FIGS. 1 and 3 and is best understood by comparing the relative lengths of the facet edges (401) and (403). The facet edge (403) is the edge formed between two adjacent pavilion main facets such as the pavilion shoulder main facet (305) and pavilion belly main facet (303) which is element indicated by this reference shown in FIG. 3. The facet edge (401) is the edge between the two half facets (307) and (309) between the same two mains as also indicated. It should be recognized, that while (401) and (403) are indicated to be two different facet edges, they are typically only one edge so they are co-planar in at least one plane and may be co-linear. It should be recognized that mathematical specificity is not required and specific variations in the ability to accurately cut diamonds will typically result in them not being perfectly co-planar or co-linear, however, that is commonly a target arrangement.

In a typical modified brilliant, the two lengths are such that the length (403) is substantially shorter than the length (401). In the depicted embodiment, however, the length (403) is actually closer to the same length as length (401), may be equal to the length of length (401), or length (403) may even be greater than the length (401). This is generally caused by the “pushing out” of the main facets as contemplated above to give them a greater angle while still having a stone of decreased depth and enabling the facets to correctly interface with the girdle (107).

While the above provides for the arrangement of facets for an oval brilliant cut, it would be understood by one of ordinary skill in the art how to adapt the above for other fancy cuts, and even for round cuts. For example, for a marquise cut, each pavilion face main facet (301) would typically not reach the cullet (11) and the pavilion thee halves (209) would be positioned so as to produce a sharper point. A pear shape would incorporate a single pavilion face main facet (301) as shown in FIG. 3 at the base of the pear and a pavilion face main facet (301) at the point in the manner of a marquise as above. A pillow cut will commonly simply have a much more squared shape than the oval which may result in the pavilion belly main facets (303) not reaching the cullet (119) or having slightly different angle.

Finally, the above principles may be used on a round cut, with any differences between the pavilion belly main facets (303) and the pavilion face main facets (301) generally being eliminated as these would generally be identical facets. It should be recognized that the cut is generally not preferred for a round cut stone as a round cut does not have clearly defined pavilion shoulder main facets (305) as effectively all the main facets are the same. Therefore, having to have each alternating, main facet (which is effectively the positioning of the pavilion shoulder main facets (305) compared to the others) have a reduced angle will produce a stone which is not cut symmetrically around a center axis. As such symmetry is usually preferred for round cuts, the present embodiment may produce a less desirable round cut than it does for others.

The qualifier “generally” and similar qualifiers, as used in the present ease, would be understood by one of ordinary skill in the art to accommodate recognizable attempts to conform a device to the qualified term, which may nevertheless tall short of doing so. This is because terms such as “planar” are purely geometric constructs and no real-world component is a true “plane” in the geometric sense. Variations from geometric and mathematical descriptions are unavoidable due to, among other things, manufacturing tolerances and individual manufacturing skill resulting in shape variations, detects and imperfections, non-uniform thermal expansion, and natural wear. Moreover, there exists for every object a level of magnification at which geometric and mathematical descriptors fail due to the nature of matter. One of ordinary skill would thus understand the tem “generally,” and relationships contemplated herein regardless of the inclusion of such qualifiers, to include a range of variations from the literal geometric meaning of the term in view of these and other considerations.

While the invention has been disclosed in conjunction with a description of certain embodiments, including those that are currently believed to be the preferred embodiments, the detailed description is intended to be illustrative and should not be understood to limit the scope of the present disclosure. As would be understood by one of ordinary skill in the art, embodiments other than those described in detail herein are encompassed by the present invention. Modifications and variations of the described embodiments may be made without departing from the spirit and scope of the invention.

It will further be understood that any of the ranges, values, properties, or characteristics given for any single component of the present disclosure can be used interchangeably with any ranges, values, properties, or characteristics given for any of the other components of the disclosure, where compatible, to form an embodiment having defined values for each of the components, as given herein throughout. Further, ranges provided for a genus or a category can also be applied to species within the genus or members of the category unless otherwise noted. 

1. A cut gemstone including: a crown and a pavilion separated by a girdle, each of said crown and said pavilion being cut to have multiple facets, said pavilion facets including: a cullet facet; belly main facet contacting said girdle facet and said cullet facet; a face main facet contacting said girdle facet but not said cullet facet; a shoulder main facet between said belly main facet and said face main facet; at least two pavilion half facets between said belly main facet and said shoulder main facet; and at least two pavilion half facets between said shoulder main facet and lace main facet; wherein said belly main facet has a facet angle between 28 and 38 degrees; wherein said face main facet has a facet angle between 28 and 38 degrees; and wherein a total depth of said gemstone is between 35 percent and 55 percent of a dimeter of said girdle.
 2. The cut gemstone of claim 1 wherein said cut gemstone is a cut diamond.
 3. The cut gemstone of claim 1 wherein said gemstone girdle is generally an oval.
 4. The cut gemstone of claim 1 wherein said gemstone girdle is generally a marquise.
 5. The cut gemstone of claim 1 wherein said gemstone girdle is generally a pear.
 6. The cut gemstone of claim 1 wherein said gemstone girdle is generally a cushion.
 7. The cut gemstone of claim 1 wherein: said crown has a crown angle; said pavilion has a pavilion angle; and said crown angle is greater than said pavilion angle by between 6 degrees and 12 degrees inclusive.
 8. The cut gemstone of claim 1 wherein a twist angle of said pavilion is between 30 and 40 degrees.
 9. The cut gemstone of claim 1 wherein said shoulder main facet has a facet angle of between 25 and 33 degrees.
 10. The cut gemstone of claim 1 wherein said facet angle of said shoulder main facet is less than said facet angle of said ace main facet.
 11. The cut gemstone of claim 1 wherein said cullet is in the shape of an elongated hexagon.
 12. The cut gemstone of claim 1: wherein, said shoulder main facet and said belly main facet meet at a first portion of a line of intersection; wherein, said at least two pavilion half facets between said shoulder main facet and said belly main facet meet at a second portion of said line of intersection; and wherein, said first portion of said line of intersection is equal to or longer than said second portion of said line of intersection.
 13. The cut gemstone of claim 1 wherein said crown includes a kite facet, at least two crown half facets, a table, and a star facet.
 14. The cut gemstone of claim 13 wherein an average table diameter is between 54 and 64 percent of an average diameter of said girdle.
 15. The cut gemstone of claim 13 wherein said cut gemstone includes 58 total facets.
 16. The cut gemstone of claim 1 wherein said shoulder main facet contacts said girdle facet and said cullet facet.
 17. The cut gemstone of claim 1 wherein said cullet has an average diameter of less than 5 percent the average diameter of the girdle.
 18. A cut gemstone including: a crown and a pavilion separated by a girdle, each of said crown and said pavilion being cut to have multiple facets, said pavilion facets including: a cullet facet; a belly main facet contacting said girdle facet but not said cullet facet; a face main facet contacting said girdle facet but not said cullet facet; a shoulder main facet between said belly main facet and said face main tweet; at least two pavilion half facets between said belly main facet and said shoulder main facet; and at least two pavilion half facets between said shoulder main facet and face main facet; wherein said belly main facet has a facet angle between 28 and 36 degrees; wherein said face main facet has a facet angle between 30 and 36 degrees; and wherein a total depth of said gemstone is between 35 percent and 55 percent of a diameter of said girdle.
 19. The cut gemstone of claim 18: wherein, said shoulder main facet and said belly main facet meet at a first portion of a line of intersection; wherein, said at least two pavilion half facets between said shoulder main facet and said belly main facet meet at a second portion of said line of intersection; and wherein, said first portion of said line of intersection is equal to or longer than said second portion of said line of intersection.
 20. The cut gemstone of claim 18 wherein a twist angle of said pavilion is between 30 and 40 degrees. 